The electrocardiogram (ECG) has proven over the years to be the single most effective clinical record for the diagnosis of cardiac muscle and cardiac nervous conduction abnormalities. An electrocardiogram is routinely taken not only on patients suspected of having cardiac disease but also on normal patients to establish base line cardiac data. Thus, millions of ECG tracings are recorded yearly in private physicians' offices and in hospitals. It is imperative that these tracings be reliable and also that they be obtained rapidly to minimize the cost. It is to these objectives that the present invention is directed.
Generally, the ECG is comprised of twelve distinct records (i.e., tracings) which are obtained from a combination of specific electrical signals obtained from the body of the patient. These signals result from the heart's electrical activity which is conducted throughout the body. The signals, ordinarily in the millivolt range, may be sensed by metal electrodes making electrical contact with the body by way of electrically conductive electrode paste. The signals are transmitted from the electrodes through cables to an electrocardiograph or ECG recorder which includes amplifying circuitry, a heat stylus writing mechansim and switching circuitry. The latter circuitry permits combining the signals ordinarily taken from ten different positions on a patient's body to obtain the twelve tracings ordinarily desired. The twelve tracings, ordinarily adequate to obtain the heart's full spectrum of electrical data, are obtained from electrodes placed on the patient's four extremities and six electrodes carefully positioned on the precordium (i.e., the chest wall of the heart area). The latter six electrodes in the precordial positions are designated as V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.5 and V.sub.6. In certain cases other positions on the chest may be chosen (e.g. V.sub.3 R) so that the specific example using positions V.sub.1 to V.sub.6 is illustrative rather than limiting.
The usual practice is to apply the electrodes to the arms (LA, RA), legs (LL, RL) and precordium (V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.5 and V.sub.6), with the electrodes being of a clamp type, suction cup type or adhesive type. Such electrodes must be applied one-at-a-time and, in the case of the precordial electrodes particularly require careful placing at specific anatomical locations. Thus, the careful and time consuming attention of a skilled nurse or doctor is required.
It is accordingly an object of the present invention to provide novel and improved method and apparatus for rapidly applying electrocardiograph electrodes to a patient's body in clinically acceptable anatomic regions.
Another object of the invention is to provide novel and improved method and means for applying the precordial electrodes simultaneously and in clinically acceptable anatomic areas on the patient's chest despite a wide range of chest sizes and configurations.
A further object of the invention is to provide novel and improved method and means for applying precordial electrodes in clinically acceptable positions on a patient's chest while facilitating the connection of leads to extremity electrodes to the electrocardiograph equipment.
An additional object of the invention is to provide novel and improved method and means for interconnecting leads from electrodes on a patient's body to electrocardiograph equipment.
These and other objects are attained by providing a chest piece including a strip of stretchable material with precordial electrodes spaced in clinically acceptable anatomic areas for a chest of small size and a holder for securing the strip in stretched position across a chest of larger size to cause the precordial electrodes to contact acceptable anatomic areas of that chest.
In a preferred embodiment, conductive connector rings at the ends of the chest piece may be individually connected electrically to the precordial electrodes. In addition, conductive connector hooks disposed on means on the holder for clamping the chest piece in position may be individually connected to conductors of a multi-conductor cable. The location of the connector hooks on the holder may be longitudinally adjustable to vary the amount the chest piece is stretched to conform with the size of the patient's chest. The hook means may also include terminals for receiving the ends of leads from electrodes on the extremities (arm and leg) on the corresponding side of the patient and these terminals may be connected to additional conductors in the multi-conductor cables.
The holder may be in the form of a strip having first slidable bars slidably adjustable longitudinally thereof, with each of these bars including another slidable bar slidably adjustable in a transverse direction.
The multi-conductor cables from both holder hook means, or transversely adjustable, may be connected to a terminal block. This block may have ten terminals representing connections respectively to the four extremity electrodes RA, LA, RL and LL and the six precordial electrodes V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.5 and V.sub.6. Where the tracings of a monitoring operation are to be connected to a five-lead (RA, RL, LA, LL and V) electrocardiograph recorder, an adapter switch box may be provided between the connecting block and the recorder so that switching between the six precordial leads may be made directly at the switch box. This switch box is also useful for increasing the speed and convenience of using a five-lead or single V-channel recorder even where the input leads of the switch box are connected to the various electrodes by other arrangements than the novel chest piece of the present invention.